1. Field of the Invention
The present invention relates to an optical fiber cable fixing mechanism in a plug, utilizing tension resistant fibers in an optical fiber cable being inserted through and retained by the plug as means for fixing the optical fiber cable to the plug against the tension exerted onto the optical fiber cable.
2. Description of the Prior Art
Generally, as shown in FIG. 1(A), an optical fiber cable 1 comprises an inner insulator 7 surrounding an optical fiber, an outer insulator 4, and tension resistant fibers 3 inserted into the outer insulator 4 so as to surround the inner insulator 7. The tension resistant fibers 3 lacking in expansion and contraction are in advance exposed to the outside from the terminal end of the outer insulator 4 and arrayed in the shape of an open umbrella. The optical fiber cable 1 is inserted through and retained in a plug 2 by screwing a male plug member 5 into a female plug member 6 to urge the umbrella-shaped fibers 3 to the bottom of a screw hole in the female plug member 6 with the leading end of the male plug member 5, thereby fastening and fixing the optical fiber cable 1 within the plug 2. At this time, the inner insulator 7 surrounding the optical fiber and projecting from the umbrella-shaped fibers 3 is passed through an aperture formed in the central bottom of the screw hole of the female plug member 6 to extend out of the female plug member 6. Thus, the optical fiber cable is fixed against the tension exerted thereonto and the inner insulator 7 is prevented from being shifted (such as disclosed in Japanese Utility Model Public Disclosure No. 58-126413).
Use of the fibers 3 lacking in expansion and contraction as means for fixing the optical fiber cable 1 against the tension exerted thereonto is very advantageous because large resistance force against the tension can be obtained. With the prior art optical fiber cable fixing mechanism, however, the fibers 3 must be cut so as to be arrayed in the shape of an open umbrella. This operation is very cumbersome and time-consuming. Further, in the prior art, the optical fiber cable is fixed by producing tension in a direction reverse to the male plug portion driving direction on the basis of the friction produced between the folded-back portions of the umbrella-shaped fibers 3 and the inner wall of the female plug member 6 by the driving force of the male plug member 5 into the female plug member 6. The friction produced by the driving of the male plug member 5 into the female plug member 6 is not always constant and, therefore, sufficient tension of the terminal ends of the fibers 3 in the aforesaid reverse direction is not always constant, either. For this reason, there is a possibility of the folded-back portions of the fibers 3 being slackened, thereby failing to obtain satisfactory fixing of the optical fiber cable 1 against the tension.